Why does my 95 Mustang GT 5.0 engine idle rough?

105

Asked by Jun 05, 2012 at 09:15 PM about the 1995 Ford Mustang GT Coupe

Question type: Maintenance & Repair

I think my water pump is on it's way out. There is a noise from that area of the motor but I can't tell if
it's the water pump or the idler/tensioner pulley (on top). The engine idles rough and also stalls out.
Mileage has been getting progressively worse as the noise is getting louder. Could either one of these
cause the engine to stall and decrease fuel mileage? I know it's not the alternator because it is new
and not the source of the noise. Also the coolant temp gage moves up and down with the RPM's. Any
feedback would be greatly appreciated. Thanks.

14 Answers

254,795

If the bearing is bad on the water pump it will make noise, and leak. But since you said it was the front of the motor, and it stalls, I will say your fan clutch is shot. With the engine off, try to spin the fan blade by hand. A normal fan clutch will spin about a half to full rotation. I suspect you won't be able to move your. Make sure when you get a new one, you get a thermatic one.

2 of 2 people found this helpful.
105

ok sorry upon closer review it is not the water pump but looks to be the oil pump. there is no fan clutch as the rad has been replaced and an electric fan added. what ever it is has similar size hose going to the engine crank case area.....

1 of 1 people found this helpful.
3,285

if your oil pump makes noise I'd be tradin the car off !!

3,285

tune it up with a new cap and rotor,spark plugs and a good set of plug wires ..

3 of 3 people found this helpful.
254,795

Hmm, oil pump? I think maybe you mean the Harmonic Balancer? The rubber gasket inside tends to wear, adding drag to the motor? Do you notice a wobble at idle? http://www.ehow.com/how_8055804_replace-mustang-5-liter-engine.html

3,285

did you mean the power steering pump ?

105

I know it is not PS pump. and not harmonic balancer either. There is a pump of some sort at the bottom left - looking at the front of the motor. the noise may be normal but I can't be sure. The only other thing is that the coolant temp. gage moves with the pulsing idle........

2 of 2 people found this helpful.
465

IN THE OLD DAYS ROUGH IDLE WAS USUALLY POINTS, BUT SINCE YOU DON'T HAVE POINTS. I THINK PETER HAS IT. DO A FULL, COMPLETE TUNE-UP.

105

I have a large manual to look at and the troubleshooting options are vast but I do think it has to do with coolant. it surprisingly was the first option to look at and I think it is valid. I have a high performance distributor cap, rotor, plugs and wires and not old enough to cause the idle issue -- in my opinion. it does seem electrical - perhaps one of the many censors. I work full time and dont have a lot of time to research this. I am just reading up on it and slowly eliminating possibilities..... for now..... thx Denis for weighing in...:)

3,285

never assume your cap is'nt cracked and if yo made the wires from a cut and fit set don't assume one end is'nt burned off either . all it takes is a bad crimp or a cut in the silicone jacket of a wire even under the boot . it'll miss like the dickens ... your high perf cap is all the more reason to check it ... ECHLIN from the napa store used to make the best caps ...

2 of 2 people found this helpful.
3,285

also check the reluctor air gap if it has one ... with a .008 brass feeler gauge .. if the dist shaft is wobbly then thats your problem .... PBN

2 of 2 people found this helpful.
3,285

well even the super genius has a brain fart now and then .... Smog pump , or as the technoids would say AIR injector pump.. this unit pumps air into the exhaust manifold after a certain speed is reached .. the additional air in the exhaust system fortifies the volcano reaction taking place in the catalitic converter which burns up leftover co2 , hydrocarbons ,Nox ,etc...

3 of 3 people found this helpful.
105

EUREKA!!!! Yes Peter that is exactly the unit. I followed the line off it and it leads to where the cat converters used to be. looks like bolts have been braised into the 2 openings it leads too. FYI I bought the car this way and have done none of the work to it. Now my question is -- can I by-pass that pump with a smaller serpentine belt.....one that is designed for the same motor minus the A/C??? And would this effect engine performance if it is possible to omit that pump all together??

3,285

If your cat. has been removed and the plumbing plugged , I can see no reason at all why you need to have the pump turning . I f you can find the right belt set up that will eliminate the smog pump I think you will be OK . just make double sure all the plumbing is plugged between the exhaust system and the smog pump or exhaust back pressure will burn out the check valve and blow thru the smog pump . PBN

Your Answer

Mustang

Looking for a Used Mustang in your area?

CarGurus has 37,626 nationwide Mustang listings starting at $895.

ZIP:

Ford Mustang Experts

  • #1
    Tom Demyan
    Reputation
    4,590
  • #2
    Bob Beaman
    Reputation
    1,260
  • #3
    COMETGUY61
    Reputation
    1,110
View All

Related Models For Sale

Used Chevrolet Camaro
416 Great Deals out of 30,636 listings starting at $3,550
Used Chevrolet Corvette
277 Great Deals out of 20,545 listings starting at $2,990
Used Ford Mustang SVT Cobra
9 Great Deals out of 290 listings starting at $5,981
Used Ford F-150
2,293 Great Deals out of 183,552 listings starting at $699
Used BMW 3 Series
1,144 Great Deals out of 32,951 listings starting at $1,300
Used Jeep Wrangler
308 Great Deals out of 16,181 listings starting at $2,500
Used BMW M3
48 Great Deals out of 1,831 listings starting at $6,500
Used Honda Civic
787 Great Deals out of 72,311 listings starting at $1,350

Used Cars For Sale

2018 Ford Mustang For Sale
226 listings starting at $26,005
2017 Ford Mustang For Sale
57 Great Deals out of 17,054 listings starting at $17,490
2016 Ford Mustang For Sale
126 Great Deals out of 3,378 listings starting at $15,391
2015 Ford Mustang For Sale
103 Great Deals out of 3,002 listings starting at $12,995
2014 Ford Mustang For Sale
86 Great Deals out of 2,866 listings starting at $10,595

Content submitted by Users is not endorsed by CarGurus, does not express the opinions of CarGurus, and should not be considered reviewed, screened, or approved by CarGurus. Please refer to CarGurus Terms of Use.